Compositions and methods for preventing sporadic neoplasia in colon

ABSTRACT

Compositions and methods for preventing sporadic neoplasia of the colon are provided. The compositions provided are be on administration of acetylsalicylic acid.

This application claims the benefit of U.S. Provisional Application No.60/361,251 filed Mar. 1, 2002 and U.S. Provisional Application filedFeb. 26, 2003 (application number not yet assigned).

This invention was supported in part by funds from the U.S. government(National Cancer Institute Grant No. RO1-CA59005). The U.S. governmentmay therefore have certain rights in this invention.

BACKGROUND OF THE INVENTION

Neoplasia of the large bowel, colon or rectum is one of the most commonforms of cancer, second only to lung cancer as a cause of cancer deathin the United States. The etiology for most cases of large bowel cancerappears to be environmental, with much research having been focused ondietary links to cancer of the colorectum. Although as many as 25% ofpatients with colorectal cancer may have a family history of the disease(most evident in Familial Adenomatous Polyposis (FAP) or HereditaryNon-Polyposis Colon Cancer (HNPCC)) the majority of patients have nosuch family history and are said to have sporadic neoplasia. Once atumor has been detected, treatment involves surgical removal of thetumor and often large portions of the affected colon.

Dietary alteration has been well studied as a method to reduce the riskof colon cancer. Although two of the risk factors for development of thedisease were thought to be ingestion of high levels of animal fat andingestion of a diet low in fiber, clinical trials have shown thatreduction in dietary fat and increases in dietary fiber may not reducethe risk of colorectal neoplasia. Other efforts at reducing the risk ofdevelopment of colon cancer have focused on intake of calciumsupplements, which may inactivate bowel carcinogens through formation ofinsoluble soaps (Mayer (1994) In: Harrison's Principles of InternalMedicine, Chapter 257, pgs. 1424-1428) or may affect cancer risk througheffects mediated by the extracellular calcium sensing receptor(Lamprecht and Lipkin (2001) Annals New York Academy of Sciences952:73-87).

Aspirin (acetylsalicylic acid), an inhibitor of arachidonic acidmetabolism, has been shown to inhibit the growth of colon tumors inrodents. Studies have also suggested that aspirin use is protectiveagainst carcinogenesis in the large bowel (Greenberg, et al. (1993) J.Natl. Cancer Inst. 85:912-916; Giovannucci, et al. (1995) New Engl. J.Med. 325:1593-1596). Several studies have also shown that sulindac, anon-steroidal anti-inflammatory drug, may have use as a preventativetreatment for hereditary polyposis of the colon and rectum (Labayle, etal. (1991) Gastroenterology 101:635-639; Ladenheim, et al. (1995)Gastroenterology 108:1083-1087; Giardiello, et al. (1993) New Engl. J.Med. 328:1313-1316). However, there remains a need for substances thatcan prevent colon cancer in humans.

SUMMARY OF THE INVENTION

An object of the present invention is a composition that can preventsporadic neoplasia of the large bowel that comprises an effective amountof acetylsalicylic acid and a pharmaceutically acceptable vehicle.

Another object of the present invention is a method for preventingsporadic neoplasia of the large bowel in a patient that comprisesadministering to a patient an effective amount of an acetylsalicylicacid composition so that sporadic neoplasia of the large bowel isprevented.

These and other aspects of the present invention are set forth in moredetail in the following description of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Although observational (epidemiological) studies have suggested thataspirin, known by the chemical name of acetylsalicylic acid, isprotective against carcinogenesis in the large bowel, there haspreviously been no experimental evidence in humans that woulddefinitively link use of acetylsalicylic acid as a treatment to preventcancer in humans. In order to provide such definitive evidence of atherapeutic effect in humans, clinical, randomized trials are routinelyperformed. It has now been found that in a randomized, double-blind,placebo-controlled study in humans that acetylsalicylic acid protectsagainst the recurrence of large bowel neoplasia in patients withsporadic (non-hereditary) colorectal neoplasia (adenomas). A 19 percentreduction in risk of one or more adenomas was found for 81 mg aspirin, anon-significant 4 percent reduction with 325 mg aspirin, and anon-significant 12 percent reduction for both aspirin groups combined.More than a 40% reduction in risk for advanced lesions with 81 mgaspirin was found. Therefore, acetylsalicylic acid (aspirin) is aneffective treatment for prevention of colon cancer in humans.

A multi-center, randomized, double-blind, placebo-controlled study wasperformed that examined the effects of aspirin alone as well as folatetreatment combined with aspirin on the occurrence of large boweladenomas. The study has a 3-by-2 factorial design, investigating aspirin(placebo, 81 mg/day, or 325 mg/day) and folic acid (placebo or 1mg/day). Patients were recruited at nine centers in North America.Eligible subjects had at least one of the following: (1) one or morehistologically confirmed large-bowel adenomas removed within 3 monthsprior to recruitment, (2) one or more histologically confirmedlarge-bowel adenomas removed within 16 months before recruitment and alifetime history of 2 or more confirmed large-bowel adenomas, or (3) ahistologically confirmed large-bowel adenoma at least 1 cm in diameterremoved within 16 months before recruitment. Each subject was alsorequired to have had a complete colonoscopy within 3 months ofrecruitment, with no known large bowel polyps remaining. Eligiblesubjects were between 21 and 80 years old, in good health, and withanticipated colonoscopic follow-up three years after the qualifyingexamination. Exclusion criteria included a history of a familialcolorectal cancer syndrome, invasive large-bowel cancer, malabsorptionsyndromes, any condition potentially worsened by supplemental aspirin orfolic acid, or any condition commonly treated with aspirin,non-steroidal anti-inflammatory drugs (NSAIDs), or folate (e.g.,recurrent arthritis, atherosclerotic vascular disease, folic aciddeficiency).

Of the 1,409 eligible subjects that were considered for the study, 1,121were randomized to aspirin. 288 subjects were not randomized due todeath, bleeding or other apparent toxicity, an inability to avoid studyagents, ineligibility for reasons related to the folate component of thestudy (e.g., anemia), intercurrent illness, non-compliance, anddeclining to continue. In the case of the folate aspect of the study,only 1,121 patients were randomized because 100 subjects had beenentered into the aspirin study before the folate arms were initiated.The numbers of randomized patients ranged from 97 to 157 across clinicalcenters. There were no substantial differences between baselinecharacteristics treatment groups in terms of demographic, lifestyle orclinical characteristics (Table 1). TABLE 1 81 mg 325 mg Placebo AspirinAspirin N = 372 N = 377 N = 372 Mean Age, years (SD) 57.4 (9.9) 57.3(9.9) 57.7 (9.1) Male N, (percent)  233 (62.6)  244 (64.7)  235 (63.2)Race White, not Hispanic, N  307 (82.5)  329 (87.3)  322 (86.6)(percent) Black, not Hispanic, N   27 (7.3)   22 (5.8)   19 (5.1)(percent) Hispanic, N   27 (7.3)   16 (4.2)   18 (4.8) (percent)Asian/Pacific/Other, N   11 (3.0)   10 (2.6)   13 (3.5) (percent) Meanbody mass index, 27.3 (4.4) 27.3 (4.4) 27.7 (4.7) kg/m² (SD) Currentcigarette smoker, N   53 (14.3)   59 (15.7)   55 (15.9) (percent)Colorectal cancer in 1^(st) degree  105 (28.2)  111 (29.4)  125 (33.6)relative, N (percent) Mean number of reported  2.4 (2.2)  2.2 (2.0)  2.4(2.4) lifetime adenomas before randomization, (SD) Qualified for studywith 1  166 (44.9)  177 (47.1)  171 (46.1) lifetime adenoma, N (percent)Qualified for study with  124 (33.3)  108 (28.6)  127 (34.1) adenoma ≧1cm, N (percent) Mean number of adenomas on  1.6 (1.0)  1.6 (1.0)  1.6(1.0) examinations qualifying for study entry (SD) Mean estimateddiameter of  0.7 (0.5)  0.7 (0.5)  0.7 (0.5) largest qualifying adenoma,cm (SD) Mean baseline dietary calcium  780 (436)  737 (366)  759 (463)intake, mg (SD) Mean baseline dietary folate  328 (161)  313 (158)  319(151) intake, μg (SD)Data on smoking status were missing for five patients, data on body-massindex, reported adenomas before randomization, and qualification for thestudy with history of 1 adenoma were missing for four patients, and dataon dietary information were missing for 55 patients.

1,084 randomized subjects (96.7 percent) underwent a follow-upexamination (Table 2), and in 1,049 (96.8 percent), the entirelarge-bowel mucosa was visualized. TABLE 2 81 mg 325 mg Placebo AspirinAspirin N = 372 N = 377 N = 372 Number of subjects (percent) Died, N(percent)   3 (0.8)   3 (0.8)   4 (1.1) No follow-up examination, N   5(1.3)   7 (1.9)   13 (3.5) (percent) Follow-up examination only   1(0.3)   1 (0.3)   0 (0.0) in 1^(st) year after randomization, N(percent) Had follow-up examination at least 1 year after randomization,N (percent) Total number evaluated  363  366  355 In protocol window 318 (87.6)  332 (90.7)  309 (87.0) Early follow-up exam   10 (2.8)   10(2.7)   9 (2.5) Late follow-up exam   35 (9.6)   24 (6.6)   37 (10.4)Entire large bowel mucosa  349 (96.1)  357 (97.5)  343 (96.6) wellvisualized Had interim* endoscopy   12 (3.3)   12 (3.3)   18 (5.1) N(percent) Mean follow-up interval, 32.9 (4.2) 32.5 (3.4) 32.8 (3.7)months (SD)*exam after randomization prior to surveillance exam.

Study coordinators at each center maintained contact with the subjectson a regular basis; interval questionnaires regarding possible sideeffects and medical events were completed every four months by eachsubject. Reported compliance with the study protocol was excellent, andwas similar across treatment groups (Table 3). TABLE 3 Placebo 81 mgaspirin 325 mg aspirin (N = 363) (N = 366) (N = 355) Number ofsubjects/total number (percent) Adherence to Study Tablets Year 1 6-7days per week 333/358 (93.0) 338/357 (94.7) 332/351 (94.6) 3-5 days perweek  19/358 (5.3)  9/357 (2.5)  11/351 (3.1)  <3 days per week  6/358(1.7)  10/357 (2.8)  8/351 (2.3) Year 2 6-7 days per week 315/353 (89.2)324/358 (90.5) 317/349 (90.8) 3-5 days per week  18/353 (5.1)  17/358(4.7)  16/349 (4.6)  <3 days per week V20/353 (5.7)  17/358 (4.7) 16/349 (4.6) Year preceding follow-up exam 6-7 days per week 298/342(87.1) 317/353 (89.8) 301/342 (88.0) 3-5 days per week  15/342 (4.4) 20/353 (5.7)  20/342 (5.8)  <3 days per week  29/342 (8.5)  16/353(4.5)  21/342 (6.1) Non-Protocol Non-Steroidal Anti-Inflammatory DrugUse Year 1 none 259/359 (72.1) 269/361 (74.5) 262/352 (74.4) 1-4days/month  86/359 (23.9)  77/361 (21.3)  78/352 (22.2)  >4 days/month 14/359 (3.9)  15/361 (4.2)  12/352 (3.4) Year 2 none 246/356 (69.1)250/362 (69.1) 251/352 (71.3) 1-4 days/month  87/356 (24.4)  87/362(24.0)  75/352 (21.3)  >4 days/month  23/356 (6.5)  25/362 (6.9)  26/352(7.4) Year preceding follow-up exam none 227/351 (64.7) 248/359 (69.1)226/346 (65.3)  1 day/month  91/351 (25.9)  79/359 (22.0)  87/346 (25.1) >4 days/month  33/351 (9.4)  32/359 (8.9)  33/346 (9.5)Only subjects who underwent a follow-up examination at least one yearafter randomization are included in this analysis. Table entries arebased on the numbers of patients who responded to intervalquestionnaires regarding compliance.

During the first year of participation, 94.1 percent of subjectsreported taking virtually all study tablets, and another 3.7 percentreported taking at least half. Even in the year before the finalfollow-up colonoscopy, 88.3 percent of subjects reported taking 90percent or more of the study tablets and another 5.3 percent at leasthalf. Subjects were also successful in avoiding non-protocol use ofaspirin and other non-steroidal anti-inflammatory drugs (NSAIDs). Duringthe first year, 73.7 percent of subjects reported no NSAID use; only 3.8percent reported taking NSAIDs on more than four days a month onaverage. In the year before the follow-up examination, these proportionswere 66.4 percent and 9.3 percent, respectively.

Among the 1,084 patients with follow-up examinations, a total of 1,812polyps were seen in 670 subjects. Fifty-eight of 664 polyps (8.7percent) in placebo subjects were lost or not removed, as were 47 of 497(9.5 percent) in the 81 mg aspirin group, and 41 of 651 (6.3 percent) inthe 325 mg aspirin group. At least one colorectal adenoma was diagnosedin 47.1 percent of subjects assigned placebo, 38.3 percent of subjectsrandomized to 81 mg/day aspirin, and 45.1 percent among those taking 325mg/day aspirin (P=0.04) (Table 4). TABLE 4 N with adenoma/N RelativeAdjusted followed Crude Risk Relative Risk (percent) (95% CI) Pvalue^(#) (95% CI)* P value^(#) Any Adenoma Placebo 171/363 1.00 1.00(47.1%) (reference) (reference) Aspirin 300/721 0.88 (0.77-1.02) 0.89(0.77-1.03) (41.6%) 81 mg 140/366 0.81 0.83 Aspirin (38.3%) (0.69-0.96)(0.70-0.98) 325 mg 160/355 0.96 0.06 0.95 0.14 Aspirin (45.1%)(0.81-1.13) (0.80-1.12) Advanced Lesion Placebo  47/363 1.00 1.00(12.9%) (reference) (reference) Aspirin  66/721 0.71 0.70  (9.2%)(0.50-1.00) (0.49-0.99) 81 mg  28/366 0.59 0.58 Aspirin  (7.7%)(0.38-0.92) (0.37-0.90) 325 mg  38/355 0.83 0.15 0.83 0.13 Aspirin(10.7%) (0.55-1.23) (0.55-1.23) Tubular Adenoma** Placebo 143/363 1.001.00 (39.4%) (reference) (reference) Aspirin 262/721 0.92 0.93 (36.3%)(0.79-1.08) (0.79-1.10) 81 mg 121/366 0.84 0.87 Aspirin (33.1%)(0.69-1.02) (0.72-1.05) 325 mg 141/355 1.01 0.06 1.00 0.16 Aspirin(39.7%) (0.84-1.21) (0.83-1.20)CI denotes confidence interval.^(#)P-values for difference between risk ratios for 81 mg aspirin and325 mg aspirin.*Risk ratios have been adjusted for age, sex, clinical center, length offollow-up and baseline number of lifetime adenoma.

The crude relative risk (versus placebo) for 81 mg/day of aspirin was0.81 (95 percent confidence interval: 0.69 to 0.96) and for 325 mg/day,0.96 (95 percent confidence interval: 0.81 to 1.13) (P fordifference=0.06). The unadjusted risk ratio for the two aspirin groupscombined was 0.88 (95 percent confidence interval: 0.77 to 1.02).Multivariate risk ratios were similar.

Findings varied according to type of lesion. For advanced lesions, theunadjusted risk ratios were 0.59 (95 percent confidence interval: 0.38to 0.92) for 81 mg aspirin, and 0.83 (95 percent confidence interval:0.55 to 1.23) for those randomized to 325 mg (P for difference ofrelative risks=0.15). Colorectal cancer was diagnosed in one subject inthe placebo group, two in the low-dose aspirin group, and three in thehigher-dose aspirin group (p=0.71). Findings were similar for adenomasin the right and left colorectum; restriction of the analysis toadenomas detected only during planned surveillance colonoscopies yieldedresults virtually identical to those above.

The reduced risk of advanced lesions with lower-dose aspirin was moreapparent among females than among males (P for interaction=0.02) andamong subjects younger than the median age (57 years old atrandomization; P for interaction=0.06). The adjusted risk ratio for thedetection of at least one advanced adenoma for 81 mg aspirin was 0.18(95 percent confidence interval: 0.06 to 0.60) among women and 0.37 (95percent confidence interval: 0.19 to 0.73) among younger subjects.

Few serious medical events were observed (Table 5). TABLE 5 81 mg 325 mgPlacebo aspirin aspirin (N = 372) (N = 377) (N = 372) P no of subjectsvalue^(‡) Deaths 3 3 4 0.93 Hospitalization 44 61 57 0.20 Non-ColorectalCancer 6 14 9 0.21 Colorectal Cancer 1 2 3 0.71 Myocardial Infarction 12 4 0.42 Coronary 4 3 5 0.76 Revascularization Stroke 0 2 5 0.06 SeriousBleeding* Gastrointestinal 3 2 4 0.65 Genitourinary 2 6 2 0.24^(‡)P values are for the differences among the three groups.*Serious bleeding was defined as bleeding leading to hospitalization orsurgical intervention.

Risks of death and serious bleeding were similar across treatmentgroups. Hospitalization, cancer and myocardial infarction occurredsomewhat more frequently in the aspirin groups than in placebo, but thedifferences were clearly compatible with chance. Seven patients werediagnosed with a stroke (all non-fatal); each had been randomized toaspirin (P for heterogeneity=0.06). One stroke (in the 81 mg aspiringroup) was judged to be hemorrhagic after review of the medical records.

The data provided herein show that the incidence of adenomas wassignificantly lower among patients randomized to the aspirin groups.Further, these data demonstrate that aspirin has a protective effect inthe large bowel, preventing the reoccurrence of neoplasia in patientswith sporadic (non-hereditary) colon cancer.

Therefore, the present invention is a composition for the prevention ofcolon cancer in humans. The composition, acetylsalicylic acid, oraspirin, was administered daily, as an oral tablet, to patients in thisclinical study. The fact that this study was a randomized, double-blind,placebo-controlled study provides significant scientific weight to theresults and demonstrates for the first time that the aspirin had atherapeutic effect. Therefore, the composition of the present inventionin one embodiment would be an orally administered effective amount ofacetylsalicylic acid. In the context of the present invention, aneffective amount of the composition of the present invention is a doseof acetylsalicylic acid of between 81 and 325 mg. In a preferredembodiment, the dose of acetylsalicylic acid would be 81 mg per day. Oneof skill would understand that the dose of the composition of thepresent invention could be altered depending on the patient populationtreated. In addition, the composition of the present invention can beadministered in forms other than tablet form that would include, but notbe limited to, geltabs, time-release capsules, oral suspensions,suppositories, topical creams or gels. Each of these formulations wouldbe chosen based on the knowledge of one of skill in the art based on thetype of treatment regimen designed for the patient to be treated.

The present invention is also a method of preventing sporadic neoplasiaof the large bowel in a patient. The method involves administering tothe patient at risk or suspected of being at risk of developing sporadicneoplasia an effective amount of acetylsalicylic acid in apharmaceutically acceptable vehicle so that sporadic neoplasia of thelarge bowel is prevented. One of skill would understand that in thismethod the pharmaceutically acceptable vehicle and the effective amountof acetylsalicylic acid would be chosen based on the patient populationto be treated. Pharmaceutically acceptable vehicles, for example, aredescribed in Remington's Pharmaceutical Sciences (16th ed., Osol, A.ed., Mack Easton Pa. (1980)). Examples of pharmaceutically acceptablevehicles include buffers such as phosphate, citrate, and other organicacids; antioxidants including ascorbic acid; low molecular weight (lessthan about 10 residues) polypeptides; proteins, such as serum albumin,gelatin, or immunoglobulins; hydrophilic polymers such aspolyvinylpyrrolidone; amino acids such as glycine, glutamine,asparagine, arginine or lysine; monosaccharides, disaccharides, andother carbohydrates including glucose, mannose, or dextrins; chelatingagents such as EDTA; sugar alcohols such as mannitol or sorbitol;salt-forming counterions such as sodium; and/or nonionic surfactantssuch as TWEEN®, polyethylene glycol (PEG), and PLURONICS®.

The invention is described in greater detail by the followingnon-limiting examples.

EXAMPLE 1 Follow-Up

Subjects were regularly counseled regarding avoidance of aspirin andother NSAIDs. Lists of products containing aspirin, ibuprofen, ornaproxen were provided, and acetaminophen was distributed for treatmentof minor febrile illnesses and pain. Every four months, subjectsreceived questionnaires regarding adherence to study treatment; use ofmedications, over-the-counter drugs and nutritional supplements; andoccurrence of symptoms, illnesses, and hospitalizations. Lists of brandand chemical names of all available NSAIDs were included in thequestionnaires, and subjects were asked if they had taken any of thelisted drugs.

By protocol, subjects were to have a complete surveillance colonoscopy34-40 months after the qualifying examination. At each colonoscopy, theendoscopist recorded the estimated size and location of all polyps andmucosal lesions suspicious for neoplasia as per usual clinical practice.Each lesion was removed and examined histologically at the clinicalcenter and by the study pathologist. Polyps were classified asneoplastic (adenomatous) or non-neoplastic (e.g., hyperplastic) by thestudy pathologist.

The primary study outcome was the proportion of subjects with one ormore colorectal adenomas detected during the period from one year afterrandomization through the anticipated surveillance follow-up. If asurveillance colonoscopy was not performed during the protocol timewindow, the last examination at least one year after randomization wastaken as the follow-up exam. Pre-specified secondary outcomes were thenumbers of large-bowel adenomas and “advanced lesions”: tubulovillousadenomas (25 to 75 percent villous features), villous adenomas (>75percent villous), large adenomas (˜1 cm), severe dysplasia, or invasivecancer. Separate analyses were also conducted for lesions in the leftcolorectum (descending colon, sigmoid colon, and rectum) and rightcolorectum (the remainder of the bowel).

EXAMPLE 2 Statistical Analysis

The statistical analysis compared the aspirin treatment groupsirrespective of folic acid treatment. Subjects who underwent a follow-upendoscopy at least one year following randomization were included in theanalyses. The predefined primary statistical analysis was a 2degree-of-freedom chi-squared test for a contingency table comparingtreatment groups regarding risk of one or more new adenomas. Crude riskratios and 95 percent confidence intervals were used to comparetreatment groups to placebo. Adjusted risk ratios were obtained fromlog-linear models with age, gender, clinical center, number of lifetimeadenomas, and duration of follow-up as covariates. Among subjects in thefull factorial trial, a blinded analysis with further adjustment forfolate treatment assignment yielded results similar to those presented.Possible modification of treatment effects by baseline characteristicswas assessed using interaction terms in the log-linear model. Counts ofother clinical endpoints were compared using Fisher's exact test. Tocompare the effect of aspirin on different types of polyps, a logisticregression model was used with generalized estimating equations (Liangand Zeger Biometrika 1986:13-22) to account for the clustering ofmultiple endpoints within patients. Poisson regression was used toestimate ratios of numbers of recurrent adenomas by treatment group;these results were similar to those in the risk analysis. Two-sidedP-values <0.05 were considered statistically significant.

1. A composition for preventing sporadic neoplasia of the large bowelcomprising an effective amount of acetylsalicylic acid and apharmaceutically acceptable vehicle.
 2. A method for preventing sporadicneoplasia of the large bowel in a patient comprising administering tosaid patient an effective amount of the composition of claim 1 so thatsporadic neoplasia of the large bowel is prevented.